Mechanical latching coordinate switch



June 4, 1968 MASAO TAKAMURA ETAL 3,

MECHANICAL LATCHING COORDINATE SWITCH Filed Sept. 12, 1966 v 5Sheets-Sheet 1 INV EN TORS na-u, cl-2c, iudlg, 4 M

' ATTORNEYS MASAO TAK'AMURA ETAL 3,387,238

' MECHANICAL LATCHING COORDINATESWITCH June 4, 1968 5 Sheets-Sheet 2Filed- Sept. 12, 1966 INVENTORS a: '0 I! I Mn, C419, 4 wklaau.

ATTORNEYs June 4, 1968 MASAO TAKAMURA ETAL. 3,

MECHANICAL LATCHING COORDINATE SWITCH Filed Sept. 12, 1966 5Sheets-Sheet 3 d 0 oil-dye (HUMW o M Jan +07% 41052 INVENTORS BY M nt;

ATTORNEYS June 968 MASAO TAKAMURA E'II'AL. 3,337,238

MECHANICAL L'ATCHINGCOORDINATE SWITCH Filed Sept. 12, 1966 5Sheets-Sheet 4 INVENTORS ATTORNEYS June 1968 MASAO TAKAMURA ETAL 3,387,33

MECHANICAL LATCHING COORDINATE SWITCH Fiied Sept. 12, 1966 5Sheets-Sheet 5 ATTORNEY United States Patent 3,387,238 MECHANICALLATCHING COORDINATE SWITCH Masao Takamura, Ichizo Nakano, and ShojiMitsuislii, Tokyo, Japan, assignors to National Telegraph and TelephonePublic Corporation, Tokyo, Japan Filed Sept. 12, 1966, Ser. No. 578,733Claims priority, application Japan, Mar. 25, 1966,

41/17,902 4 Claims. (Cl. 335-112) ABSTRACT OF THE DISCLOSURE Amechanical latching coordinate switch having a plurality of coordinatelyarranged contact groups, in each of which holding fingers and contactactuating cards are arranged in such manner that they are movable onlyin one direction, respectively, and the directions of their movementsare perpendicular to each other, resetting bars for driving the contactactuating cards in each horizontal row, electromagnetic devices fordriving said resetting bars and electromagnetic devices forsimultaneously actuating the holding fingers in each vertical column,whereby the resetting bars and the holding fingers are driven by theelectromagnetic devices to disengage the holding finger from the contactactuating card so as to maintain the desired cross-point connection andengage the both members so as to maintain the cross-point release.

This invention relates to coordinate switches to be used for switchingnetworks of telephone exchange and more particularly to coordinateswitches wherein mechanical latching is carried out with flat springfingers.

Conventional non-latching cross-bar switches such as disclosed in USPatent No. 2,350,464, have defects that (1) The inertias of theselecting bar and holding arm are so large that the operating time andreleasing time are long,

(2) As the electric energization of the holding electromagnet isrequired to hold a cross-point connection, the electric powerconsumption is large, and

(3) It is necessary that the selecting finger should be able to move inboth vertical and horizontal directions, therefore the operation is notsure, misoperations are apt to cause and the transient vibration at thetime of the operation and the release lasts long.

The conventional cross-bar switches comprises a set of contacts arrangedon horizontal rows and vertical columns, bars, each of which beingcommon to two horizontal rows, bars, each of which being common to twovertical columns, flexible linear fingers attached to the horizontalbars, operating plates with notches and an electromagnetic means fordriving rollers and bars mounted on hoding springs, whereby the linearfinger enters into the notch of the operating plate to push or withdrawthe finger and operating plate so as to operate the contacts and theroller mounted on the holding spring is fitted in the notch of theoperating plate for keeping the contacts in the operation state. Theconventional switch is required for maintaining the operation andoperating state of the contacts to provide two entirely different kindsof the holding springs provided with the finger and roller so that theswitch is complicated in its construction and becomes inevitablyexpensive. Furthermore, the wear caused by the sliding movement of therollers is not negligible. For releasing the contacts which are in theoperating position there requires the sequence of operation reversed tothat at the time of operation by changing the sequence of operation ofeach element. Therefore, in the conventional switch there is the need ofreleasing the contact 3,387,238 Patented June 4, 1968 every timet of thecompletion of a call, whereby the operation is not sure, malfunctionsare apt to result, and the transient vibration at the time of therelease las long, thus making the control of the switch complicated sothat no high speed operation can be expected.

With the recent development of electronic exchanges, it has come to bedesired to realize a switching apparatus with metallic contacts of ahigh speed, small electric power, small size and light weight as aswitching network element. As a typical switching apparatus forelectronic exchanges, the principle and embodiments of so-called Ferreedswitches are shown in The Bell System Technical Journal, vol. XLIII,September 1964, No. 5, pages 2374-2376.

They are of a system wherein a set of reed switches and a core having aproper coercive force are arranged at a cross-point and a differentialexciting winding is applied to the core so that the residualmagnetization of the core may be reversed by an exciting current, thereed switches may be operated, held or released by the combination ofthe polarities of the residual magnetization and the contacts may beoperated and released at a high speed of about 2 ms. Specifically, ifthe residual magnetization is reversed, the switches will operate.Therefore, it is a feature of this system that the exciting currentpulse may be of a time width (of about ,uSGC.) required for themagnetization reversal.

Further, if, in order to select and to connect one crosspoint, anelectric current is passed through the exciting coils of the row andcolumn to which said cross-point belongs, said cross-point contact willbe connected but all the other connected cross points belonging to thesame row and column will be released. Therefore, there is no need ofreleasing the cross-point upon the completion of a call and it is simpleand easy to control the switching apparatus.

While the Ferreed switches have the following demerit that, the excitingcurrent therein is so large (about 10 amperes) that the selectingcircuit of the exciting coil terminals cannot be composed of suchelement of high speed operation as a semiconductor device or reed relay,a large e ectromagnetic relay slow in the operation must be used.Consequently, the time required for the final connection of across-point after a control signal which identify the exciting coil hasbeen received, cannot be reduced.

Further, the Ferreed switches are comparatively so large in theoccupying volume and weight that, in the case of forming an electronicexchange apparatus the occupied space of the switching devices in thetelephone office building is very large.

Therefore, an object of the present invention is to provide a switchingapparatus operated at a high speed by eliminating the various defects ofconventional switching apparatus.

A further object of the present invention is to provide a switchingapparatus of a small electric power consumption, a small size, lightweight and low price.

A still further object of the present invention is to economicallyrealize a telephone exchange system with high serviceability.

In the accompanying drawings,

FIG. 1A is a perspective view showing the operating principle of aconventional non-self-latching cross-bar switch;

FIG. 1B is a view showing a cross-point connection in a conventionalnon-self-latching cross-bar switch;

FIG. 2A is a perspective view showing the operating principle of amechanically latching cross-bar switch of the present invention;

FIGS. 2B(a), 2B(b) and 2B(c) are elevations of FIG.

ZA showing cross-point connections in the mechanically latchingcross-bar switch of the present invention looking in the direction ofthe arrow;

FIG. 3 is a view showing an inter-stage wiring to be forbidden when amechanical latching cross-bar switch of the present invention is used;

FIG. 4 is a view showing an offering connection when a cross-bar switchof the present invention is used;

FIG. is a partly sectioned elevation of a mechanically latchingcross-bar switch of the present invention;

FIG. 6 is a perspective view illustrating the structure of a yoke of aresetting electromagnet to be'used for the cross-bar switch of thepresent invention.

The explanation of the operating principle of a non-selflatchingcross-bar switch usually used for a conventional common control exchangeis shown in FIG. 1A and the explanation of the selecting operation of across-point contact is shown in FIG. 1B. Both drawings show a pair ofcross-points belonging to one vertical column among cross-pointsarranged in a matrix. The case of selecting and connecting thecross-point on the upper side shall be explained in the following.

In FIGS. 1A and 1B, 1 is a selecting finger, 2 is a contact actuatingcard, 3 is a holding arm, 4 is a vertical unit frame, 5 is a verticalmultiple contact rod, 6 is a cross-point movable contact spring, 7 is aselecting bar for actuating the selecting finger, 8 is a holding magnetfor driving the holding arm and 9 is a pair of selecting magnets fordriving the selecting bar.

In FIG. 1A, when the selecting magnet 9 of lower side is electricallyenergized to actuate upwardly the selecting finger 1 and select ahorizontal row, the selecting finger 1 will be shifted into an operatingclearance formed by the contact actuating card 2 and holding arm 3 asshown by 1 in FIG. 1B(a). Then, if the holding magnet 8 in FIG. 1A iselectrically energized to horizontally move the holding arm 3 belongingto a desired vertical column as in FIG. 1B( b), the contact actuatingcard 2 (on the upper side of the drawing) will be pushed through thefinger 1 so that the cross-point movable contact spring 6 and thevertical multiple contact rod 5 may be electrically connected.

When a desired cross-point is selected as in the above, the electricalenergization of the selecting magnet 9 will be interrupted but theelectrical energization of the holding magnet 8 for driving the holdingarm 3 will be continued in order to maintain the cross-point connection.

Now, the fundamental principle of the mechanically latching coordinateswitch of the present invention shall be explained with reference to thedrawings.

FIG. 2A is a perspective view for explaining the operating principle ofthe mechanically latching coordinate switch of the present invention.FIG. 2B is a view for explaining a cross-point connection. Both drawingsshow four cross-points belonging to two horizontal rows and two verticalcolumns among cross-points arranged in a matrix. The case of selectingand connecting the crosspoints on the lower side shall be explained inthe following.

In FIGS. 2A and 2B, a resilient contact spring 10 made of an electricconductor and provided with a contact, a vertical multiple contact rod11 made of an electrical conductor, a holding finger 12 and a fingerdriving magnet 13 are fixed to a frame 14 made of an electricalinsulator so as to form a vertical unit. A contact actuating card 16made of an electrical insulator and provided with a projection to engagewith the holding finger is fitted to the tip of the contact spring 10.

The holding finger 12 is in the form of a fiat spring and is made of amagnetic material high in tensile strength or is made by securing amagnetic material to a resilient spring material and is formed so thatall the holding fingers mounted on the vertical unit may be directlyelectromagnetically and simultaneously attracted by the finger drivingmagnet 12 and two or more holding fingers are driven by one drivingcoil- As this holding finger is flat-shaped, it can move only verticallyin FIG. 2A but does not move horizontally due to its rigidity.

A required number of the above described vertical units are arranged andas many resetting bars 18, which are provided with projections 17 toengage with the contact actuating cards 16 corresponding to therespective cross-points of the horizontal rows as the horizontal rowsare arranged. Each resetting bar is mounted to an armature 21 of aresetting magnet 19 at one end and is tensioned with a restoring spring20 at the other end. Therefore, if the resetting magnet 19 iselectrically energized, the resetting bar 18 belonging to said magnetwill be pulled longitudinally and the contact actuating cards 16 in thesame horizontal row engaging with the resetting bar 18 at the projection17 thereof will move together with the resetting bar 18.

FIGS. 2A and 2B(a) show a state in which the projection 15 of thecontact actuating card 16 is engaged with the holding finger 12 and thecross-point is released.

In FIGS. 2A and 2B, in the case of connecting the cross-points of therow X and column Y when the resetting magnet 19 of the row X in FIG. 2Ais electrically energized by a control signal, the armature 21 will beattracted and the resetting bar 18 will move in the direction indicatedby the arrow. At this time, the contact actuating cards 16 of all thecross-points belonging to the row X will be pushed in the same directionas of the resetting bar by the projections 17 of the resetting bar and,as shown in FIG. 2B( b) the finger 12 will separate from the projection15 of the contact actuating card 16 and will be disengaged.

Then, if the finger driving magnet 13 of the column Y is electricallyenergized by a control signal in FIG. 2A, an attraction will act on allthe holding fingers 12 of the column Y but only the finger 12 of the rowX and column Y disengaged with the contact actuating card 16 will beable to move toward the magnetic pole 22 and, as in FIG. 2B(b), theholding finger will move to the position represented by 12' and will becompletely separated from the projection 15 of the contact actuatingcard 16. But, as the holding finger belonging to the column Y except atthe cross-point of the row X and column Y is subjected to the action ofthe attraction but is locked not to move by the projection 15 of thecontact actuating card 16, the holding finger and the contact actuatingcard remain engaged as they are. In this state, in FIG. 2A, if theelectrical energization of the resetting magnet 19 is interrupted, theresetting bar 18 will return due to the restoring spring 20. At thistime, the contact actuating card '16 pushed and moved by the projection17 of the resetting bar 18 will also return to the original position dueto the restoring force of the contact spring 10 or the like and willagain engage with the holding finger. But, only the contact actuatingcard 16 at the cross-point of the row X and column Y at which theholding finger 12 is separated from the contact actuating card 16 willmove together with the resetting bar 18 without being locked by thefinger 12 and the contact will be connected. Then, if the electricalenergization of the finger driving magnet 13 is interrupted, thecross-point will remain connected as in FIG. 2B(c) in a state of makingno cur-rent flow to the electromagnet.

In releasing the connected cross-point, if the resetting bar 18 isoperated as in FIG. 2B(b), the holding finger 12 will return from theposition 12 to the position 12 due to its own resiliency and then, ifthe resetting bar 18 is released, the state shown in FIG. 2B(a) will berestored. The operation of releasing the cross-point of this resettingbar 18 will be carried similarly to the case of connecting thecross-point. Therefore, if one cross-point connection is made, at leastall the other cross-points in the horizontal row belonging to saidcross-point will be released.

As evident from the above explanation, the mechanically latchingcoordinate switch has a self-latching function by using such magneticmaterial low in coercive force as pure iron for the electromagnet coreand yoke so that,

with the operation of one cross-point connection, all the other operatedcross-points belonging to the same horizontal row Will be released. Thisis different from the Ferreed switches wherein, with the operation of across-point connection, all the other operated cross-points belonging tothe same horizontal row and vertical column will be released. In themechanically latching coordinate switch, in the case of a cross-pointconnection, only the other operated cross-points belonging to the samehorizontal row will be released but the other operated cross-points inthe vertical column will not change its state.

Such cross-point selecting method as in the Ferreed switches has no needof releasing and controlling the switch upon the completion of a calland gives a convenience in the case of forming an exchanging system buthas a defect that no offering connection can be made therein.

However, there has been suggested a system wherein, in the case offorming switching network by the mechanically latching coordinateswitches, the formation and control of speech paths will be simple andan offering connection by the operator will be done easily.

Needless to say, with the completion of the call, the resetting bar isoperated to release the cross-point, there will be no problem on asubsequent network connection. Aside from it, instead of the operationof the resetting bar upon completion of a call, the followingrestricting conditions may be applied to the inter-stage wiring of v theswitching network.

FIG. 3 is a view showing an inter-stage wiring to be forbidden when acoordinate switch according to the present invention is used. Suchwiring as makes each row of the switch in one stage (ith) an outlet andmakes each row of the switch in the next stage (i+lth) an inlet as shownin FIG. 3 has a possibility of producing such crosstalk loop as is shownby the broken line for the connecting paths of a-b and c-d when theswitch is not released upon the completion of a call and is thereforeforbidden. However, if such inter-stage wiring as from column to row orfrom row to column or from column to column is made, no cross-talk loopwill be produced. Such restriction will not be so disadvantageous,especially, in the case of constructing a switching network by thesquare matrix switch, because the row and column are quite symmetricalwith each other.

Further, in the case of making a so-called offering connection ofconnecting another call to one call being made, with the Ferreed switch,when one cross-point in the switch is connected, the other cross-pointsbelonging to the same row and column will always release and thereforeit is impossible to make an offering connection within the switch. But,in the mechanically latching coordinate switch according to the presentinvention, in the case of connecting a cross-point, the othercross-points in the same row as of it will be released but thecross-points in the same column will not be influenced at all andtherefore, by utilizing this fact, an offering connection can be made.

FIG. 4 is a view showing an offering connection when the mechanicallylatching coordinate switch of the present invention is used. As shown inthe drawing, it is possible to form a connecting path with c byconnecting a contact d further to a connecting path connecting a and b.

As explained above, in the mechanically latching coor dinate switchaccording to the present invention, the resetting bar 18 in thehorizontal row will be subjected mostly to a tensile stress and can bemade very light and, as the holding finger 12 is driven directly withthe electromagnet, the mass of its moving part is very small. Further,in the mechanically latching coordinate switch, during a call, noelectric current is required to electrically energize the electromagnet,merely a pulse current may be impressed in the case of the connectingoperation, therefore the temperature rise of the exciting coil will bevery small, thus the amount of copper required for the exciting coil maybe small, the time constant of the exciting coil will become smaller andthe operating time of the switch will be reduced very much.

Further, as the holding finger is flat-shaped as different from theknown conventional selecting finger and its moving direction is limitedto one, its operation will be sure. Further, as in the mechanicallylatching coordinate switch according to the present invention theholding finger and the finger driving magnet are mounted on a verti calunit and an electromagnetic attraction may act simultaneously on allfingers of column, so the structure of the finger driving magnet can besimplified and the relative positions of the holding finger, contactactuating card and finger driving magnet with one another can berealized accurately.

In the connecting operation of the mechanically latching coordinateswitch, it is necessary to delay the movement of the holding finger 12from the movement of the resetting bar 18 a little. However, if theoperation is a little delayed by applying a copper sleeve or a barecopper winding to the finger driving magnet 13 or connecting aninductance and capacitance to the coil, the resetting magnet 19 andfinger driving magnet 13 will be able to be electrically energizedsimultaneously with the same current pulse and the control of the switchwill become easy.

FIG. 5 is an elevation of the embodiment of the present invention shownin FIG. 2A. As the vertical units Y and Y are used for pre-selection, itshows substantially a mechanically latching coordinate switch of 2wires, 8 rows and 8 columns.

FIG. 5 shows an arrangement of the contacts 10, holding fingers 12 andresetting bars 18. As explained wilh reference to FIG. 2A, the contacts10 and holding fingers 12 in the same vertical columns (Y Y Y aresecured to the unit frame 14 made of a synthetic resin by injectionmolding, together with the finger driving magnet 13 so as to form oneunit.

Now, in arranging any required number of such vertical units, if all thevertical units are fixed by being fastened with bolts 24 passing throughthe upper ends and lower ends of the vertical units on the right side ofa fixing plate 23 having the resetting magnets 19 fixed on the leftside, a formation of switches of X rows and Y columns will be made.Thus, it is easy to form an optional number of vertical units and theassembly can be made very light.

In FIG. 5, the contacts in each of the columns Y to Y are arranged intwo columns, a horizontal multiple connection is made on the backsurface of switch and the fixed contact is in the form of a verticalmultiple contact rod. In each of the vertical units of the columns Y andY the contacts are arranged in one column only backwardly. The fixedcontact and movable contact of each contact pair in the columns Y and Yare both electrically insulated in the vertical column and areindependent of each other and an electric terminal comes out on the rearside of the switch so as to make a unit for pre-selection. The left sidecontact spring terminals and the right side contact spring terminals ofthe vertical units Y to Y are horizontally multiple-wired with themovable contact spring terminals of the vertical unit Y and the movablecontact spring terminals of the vertical unit Y respectively. The fixedcontacts in the same horizontal row of the vertical units Y and Y areconnected with each other. Therefore, in the case of connecting thecrosspoint, if the holding finger 12 belonging to one of the verticalunits Y to Y and either one of Y and Y and resetting bar 18 in thedesired row are operated, a so-called pre-selective connection will bemade.

The structure shown in FIGURE 5 provides a set of two units forpre-selection but a preselective function can be obtained by one unit.That is, each contacts group of the unit for pre-selection comprises twopairs of make-break contacts, wherein the movable contact which isopened when the holding finger 12 is engaged with the contactingactuating card 16, is horizontally multiple-wired with the left sidecontact of the vertical units Y to Y while the movable contactrespectively which is closed respectively is horizontally multiple-wiredwith the right side contact of the vertical units Y to Y Further, in theunit for preselection, the fixed contact is indepedent'of each contactsand its terminal comes out on the rear side of the switch. In case ofconnecting the cross-point, if the holding finger belonging to one ofthe vertical units Y to Y are operated, a pre-selective connection willbe made, according to the location of the holding finger of the unit forpreselection.

Thus, the pro-selective connecting function can also be provided by onlyaddition of a pair of units for preselection and the number of thecross-points contained in the horizontal row can be selectively variedwith the increase of the vertical units so that the switch can easily beconstructed and is universal and can be mass-produced.

Now, though the resetting magnets are fixed on one side of the fixingframe 23 to which the vertical units are fixed, the yokes of theseelectromagnets can be made in a body and used commonly as a path ofmagnetic flux so that they may be easy to make and may be made light inthe weight and high in the speed.

FIG. 6 is a perspective view showing the structure of a yoke of aresetting magnet of a coordinate switch of the present invention. Asshown in FIG. 6, the yoke 25 is bent by press working, has a core 26arranged on one edge and is provided with a opening 27 in the part ofthe yoke 25 opposed to the core 26. This opening is effective to reducethe leaking magnetic flux between the core and the yoke and is usefulfor the high speed operation. Further, the required cross-sectional areaof the Yoke will be sufiicient if it is such that, when one resettingmagnet is electrically energized, no magnetic saturation will occur. Theamount of iron will be remarkably reduced to be smaller than in the caseof providing individual resetting magnets with independent yokes. Thus,it is useful to reduce the weight of the switch. Further, as theseresetting magnets are arranged in one column, it is easy to makeintegral the hinge lug and back stop of the resetting armature or therestoring springs 20 of the resetting bar 18 (ref. FIG. 2A) alsoarranged in one column respectively. Therefore, it is very effective tothe reduction of the number of parts and the reduction of the price ofthe switch.

The features of the mechanically latching coordinate switch of thepresent invention explained'above are 1) That it consists of verticalunits on which crosspoint contacts, holding fingers and finger drivingmagnets are mounted, horizontal resetting bars and resetting magnets,that the mass of the movable parts is so small that a high speedoperation can be made,

(2) That is a self-latching switch wherein, in the case of a cross-pointconnection, the other operated crosspoints in the same row will beautomatically released, that the connection and control of a speech pathare simple and an offering connection is possible,

(3) That the vertical unit frame and other parts are made of lightmaterials, no switch frame is required and therefore it is light andsmall, that as it is formed by making various parts integrally, thenumber of component parts is reduced and, as it is of a structure inwhich the accuracy of the assembly is obtained easily, the price is low,

(4) That, as it is formed by piling up and bolting a required number ofvertical units, in increasing the number of vertical columns, only theresetting bars may be changed and, if units for pre-selection are added,it will be a switch for pre-selection and that thus it is veryuniversal. It is well adapted to switching apparatus for electronicexchanges. Indeed, the switch realized according to this invention ismuch smaller and lighter than any conventional switch of this kind.Eachof its horizontal and vertical energizing electric powers is about50 w. Its exciting current is so small that it is possible to use thereed relay driven with the semi-conductor device in the selectingcircuit of the exciting coil terminal. Therefore, though the excitingcurrent pulse width of the switch is about 4 ms, the time which isrequired for the excitation of the switch driving magnet after thecontrol signal is received, will be greatly reduced, and the controllingapparatus will be saved, moreover the switching apparatus will be madesmall, light and cheap and thus the telephone exchange system can beeconomically constructed.

What is claimed is:

1. A mechanical latching coordinate switch comprising a plurality ofcross-point contact units having a plurality of contact groups providedwith contact actuating cards having parts engaging with holding fingersand aligned in a vertical column, a plurality of holding fingersprovided for respective contact groups and movable only in one directionperpendicular to the direction of movement of the contact actuatingcards and electro-magnetic devices for simultaneously acting on saidholding fingers; a plurality of resetting bars arranged perpendicularlyto said cross-point contact units so as to operate the contact actuatingcards of the contact groups belonged to each horizontal row of saidcross-point contact units; and resetting bar driving units provided witha plurality of electromagnetic devices driving individually saidresetting bars in a vertical column and in the same surface of saidcross-point contact units, whereby the ele .romagnetic devices drive theresetting bar and the holding finger, respectively, the holding fingerdisengages from the contact actuating card and then when the resettingbar is released, the contacts remain connected and the holding finger isprevented from its return, while when only the resetting bar is driven,the holding finger returns to engage with the contact actuating card andthe contacts remain released.

2. The mechanical latching coordinate switch claimed in claim 1, whereina plurality of units for pre-selection is added, said units having thesame construction as of the cross-point contact units except that thecontacts of each contact group are separately and independently formed.

3. The mechanical coordinate switch claimed in claim 1, wherein theindividual electromagnetic devices of the resetting bar driving unit areformed for such common yoke as has an opening in the part opposed to theside of each core.

4. The mechanical latching coordinate switch claimed in claim 1, whereinthe electromagnetic devices provided with a driving coil which is commonto more than two holding fingers in each cross-point contact unit is provided.

References Cited UNITED STATES PATENTS 2,082,911 6/1937 Schneckloth335-112 2,350,464 6/1944 Keller 3351l2 2,932,773 4/1960 Matthews 335-281BERNARD A. GILHEANY, Primary Examiner.

H. BROOME, Assistant Examiner.

